They may be protected from discrimination, depending on local law. They’re not allowed demand that a company sell them something that it would not ordinarily sell to anyone, though.
Do you think every single political or religious group would be protected? If that's the case, everyone would be in one and nobody would be "not protected".
No because you are choosing to be in one. I was not born a Methodist but my parents took me to a Methodist church as a child. I was not born with the desire or need to go to a Methodist church.
This has absolutely nothing to do with religion. Unless the Texans protesting against abortion are surprisingly not Christians but members of some other faith that forbids abortion.
Some may claim abortion is against some vague "christian values" but those people either didn't read their own holy book or use it as a thinly veiled excuse to oppress other people.
They’re selling the service to everyone with the same terms, and the Texan group’s religious beliefs are irrelevant to their violation of the TOS.